Modifying the highland barley gliadin with reducing sugar grafting and enhancing its structural and functional...

As the primary storage protein, highland barley gliadin (HBG) exhibits limitations in the processing of highland barley foods, primarily due to its abundant non-polar amino acids. In this study, HBG was utilized to prepare sugar-HBG complexes with pentose (xylose), hexoses (glucose and galactose), and disaccharides (lactose and maltose) in an aqueous system at a pH of 11 and a temperature of 75 °C. Subsequently, the structural and functional characteristics of these complexes were evaluated. The formation of the complex was verified through analysis of the degree of grafting (DG), SDS-PAGE, and SE-HPLC, and it was also confirmed that intermolecular disulfide bonds formed cross-linked aggregates with a higher molecular weight (>180 kDa). In terms of structure, there was an increase in the β-sheet content (from 32.7 % to 36 %), accompanied by decreases in particle size, the proportion of disordered structures, and surface hydrophobicity. In terms of functionality, while he glycoprotein's solubility and emulsifying ability decreased, the glycoprotein's thermal stability and foaming capacity at PH, BH, and RH significantly increased. Notably, the DPPH radical scavenging activity increased markedly, positively correlating with protein concentration and negatively with the molecular weight of sugars. At a concentration of 5 mg/mL, this activity was approximately 10 times that of HBG. In the future, glycosylated prolamin can serve as an endogenous antioxidant additive, extending the shelf life of highland barley products and broadening its applications within the food processing industry.